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Electrical System Critique

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jwt(at)roadmapscoaching.c
Guest

Posted: Tue Feb 06, 2007 8:48 pm Post subject: Electrical System Critique

I am pretty close to finalizing my  electrical system and would really like to have some knowledgeable folks give it  a rigorous critique. I have attached a Word document with my objectives, panel  layout and schematic. If any of you are willing, I would really appreciate your  taking the time to study the design and give me your recommendations.  

  

 Feel free to contact me offline or call me  at 804-303-1927

  

 Thanks in advance to those who give me some  input.

  

  John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

 Richmond, VA

FWF, engine, wiring

 do not archive

 

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sean(at)stephensville.com
Guest

Posted: Tue Feb 06, 2007 11:21 pm Post subject: Electrical System Critique

sean(at)stephensville.com
Guest

Posted: Wed Feb 07, 2007 8:43 am Post subject: Electrical System Critique

Jon Reining

Joined: 10 Jan 2006
Posts: 37

Posted: Wed Feb 07, 2007 9:26 am Post subject: Re: Electrical System Critique

This is a new product coming out on the market that looks like it may have a lot of appeal.



http://www.verticalpower.com/



Jon (and Bill) Reining

40514 - tailcone - still

rvbuilder(at)sausen.net
Guest

Posted: Wed Feb 07, 2007 10:54 am Post subject: Electrical System Critique

That is cool!  Look forward to seeing them at OSH.



Michael

Do not archive



--

marcausman

Joined: 08 Feb 2007
Posts: 70

Posted: Thu Feb 08, 2007 9:12 pm Post subject: Re: Electrical System Critique

John,



Unless you believe that you'll have a disabling catastophic failure caused by the main battery, you could simplify your system by wiring the two batteries in parallel and eliminate a contactor and switch. It may be hard to properly diagnose and manage such a failure while in flight. And if that type of failure occurred, you'd lose your attitude sources while you diagnosed the problem and switched to the backup batt. 



It sounds likes you mainly want some extra juice for starting and alternator failure, and if that's the case, wiring the batteries in parallel would take care of that and always be available.

_________________
Marc Ausman
http://www.verticalpower.com "Move up to a modern electrical system"
RV-7 IO-390 Flying

LarryRosen

Joined: 16 Jan 2006
Posts: 415
Location: Medford, NJ

Posted: Sat Feb 10, 2007 8:39 am Post subject: Electrical System Critique

John,

I have not seen much response, so I will add my 2 cents.

The list is long.  Much of which are things to consider.  The design you 

have is safe and will work just fine.  Just some of my thoughts.



I do not see anything in the equipment list to allow GPS navigation.  

Are you adding a Freeflight GPS to the Chelton?



You have a 30 amp battery bus feed that is longer than 6" it should have 

a contactor.  But the contactor would not make it a battery bus.  The 

only load that needs to be on the battery bus would be the electric 

ignition and maybe the dome lights. Then you can have a 10 amp battery 

bus. Another feed with a contactor would feed the other loads.



Why the double pole switch for the e-bus feed and the standby battery 

switch?



replace the double pole avionics master with 2 switches to eliminate the 

single point failure to the avionics bus and endurance bus.



Do you need the transponder on the e-bus?  (it is on mine also)



Consider moving the pitot and to the main bus.



Why a 50 amp ANL from the alternator.  Change to 60 and 6awg wire.  You 

show 43 amps max.  Is that with zero diversity?  I thought at one point 

you had 58 amps max intermittent load.



Why 16awg wire to the starter on light?  with a 1amp fuse you only need 

22awg.  Consider a fusable link in lieu of the fuse.  Whose starter?  I 

have not seen this wiring detail.



Starter contactor.  BNC has the diode internal, Vans does not have a 

diode.  I am using Perihelion designs snap jacks (bi-directional zener) 

in lieu of the diode.



The wire from the alternator to the ALT out light then goes to a 1 amp 

fuse/breaker on a bus.



Are you using the same fat wire from the starter contactor to the starter?



Consider using shotkey diodes everywhere.  Low voltage drop.



You have the EIS (AFS 3400) fed through diodes from both the main bus 

and the endurance bus.  This will give you an inaccurate voltage 

reading. The AFS3400 has dual power feeds pin 1 & 15.  This would give 

you voltage on the main bus  & e-bus which could be nice to have.   

Doesn't the AFS 3400 have internal diodes to prevent drain of its 

internal battery?



Do you want to power the pinpoint MSU & GADAHRS from both the Avionics 

and e-bus for some redundancy.  It also has dual power inputs.



Are you adding a switch on the panel for the pinpoint GADAHRS compass 

swing & alignment procedure (pin 16)?



Any switch to activate/deactivate the functions of the co pilot stick 

grip (assuming some sort of grip with switches)



Trim on the ebus, I would assume that is pitch trim.  How about roll 

trim?  Rudder trim?



Larry Rosen

#356

 



John Testement wrote:

 	  Quote: 	
		   I am pretty close to finalizing my electrical system and would really 

 like to have some knowledgeable folks give it a rigorous critique. I 

 have attached a Word document with my objectives, panel layout and 

 schematic. If any of you are willing, I would really appreciate your 

 taking the time to study the design and give me your recommendations.

  

 Feel free to contact me offline or call me at 804-303-1927

  

 Thanks in advance to those who give me some input.

  

 John Testement

 jwt(at)roadmapscoaching.com <mailto:jwt(at)roadmapscoaching.com>

 40321

 Richmond, VA

 FWF, engine, wiring

 do not archive



 --

_________________
Larry Rosen
#40356
N205EN (reserved)
<http>

Tim Olson

Joined: 25 Jan 2007
Posts: 2882

Posted: Sat Feb 10, 2007 5:08 pm Post subject: Electrical System Critique

I have 2 very minor notes to add.

1:  I'm finding my running load with landing lights is somewhere around

36A. (Not with flaps and trim moving).   Just a data point.

2:  As far as that pinpoint pin 16 switch, I would hide that switch

behind the panel.  You'll never use it once you are done calibrating,

and I'm not only confused as to why some dealers think it should

be there, but I think it's a bad idea.  If they insist on putting

it on the panel, insist on them not labeling it, so you can move it

somewhere else behind the panel....then stick a switch for something

else in that hole.  I've not touched mine since it was calibrated.

Tim Olson - RV-10 N104CD - Flying

do not archive

Larry Rosen wrote:

 	  Quote: 	

 John,

 I have not seen much response, so I will add my 2 cents.

 The list is long.  Much of which are things to consider.  The design you 

 have is safe and will work just fine.  Just some of my thoughts.

 I do not see anything in the equipment list to allow GPS navigation.  

 Are you adding a Freeflight GPS to the Chelton?

 You have a 30 amp battery bus feed that is longer than 6" it should have 

 a contactor.  But the contactor would not make it a battery bus.  The 

 only load that needs to be on the battery bus would be the electric 

 ignition and maybe the dome lights. Then you can have a 10 amp battery 

 bus. Another feed with a contactor would feed the other loads.

 Why the double pole switch for the e-bus feed and the standby battery 

 switch?

 replace the double pole avionics master with 2 switches to eliminate the 

 single point failure to the avionics bus and endurance bus.

 Do you need the transponder on the e-bus?  (it is on mine also)

 Consider moving the pitot and to the main bus.

 Why a 50 amp ANL from the alternator.  Change to 60 and 6awg wire.  You 

 show 43 amps max.  Is that with zero diversity?  I thought at one point 

 you had 58 amps max intermittent load.

 Why 16awg wire to the starter on light?  with a 1amp fuse you only need 

 22awg.  Consider a fusable link in lieu of the fuse.  Whose starter?  I 

 have not seen this wiring detail.

 Starter contactor.  BNC has the diode internal, Vans does not have a 

 diode.  I am using Perihelion designs snap jacks (bi-directional zener) 

 in lieu of the diode.

 The wire from the alternator to the ALT out light then goes to a 1 amp 

 fuse/breaker on a bus.

 Are you using the same fat wire from the starter contactor to the starter?

 Consider using shotkey diodes everywhere.  Low voltage drop.

 You have the EIS (AFS 3400) fed through diodes from both the main bus 

 and the endurance bus.  This will give you an inaccurate voltage 

 reading. The AFS3400 has dual power feeds pin 1 & 15.  This would give 

 you voltage on the main bus  & e-bus which could be nice to have.   

 Doesn't the AFS 3400 have internal diodes to prevent drain of its 

 internal battery?

 Do you want to power the pinpoint MSU & GADAHRS from both the Avionics 

 and e-bus for some redundancy.  It also has dual power inputs.

 Are you adding a switch on the panel for the pinpoint GADAHRS compass 

 swing & alignment procedure (pin 16)?

 Any switch to activate/deactivate the functions of the co pilot stick 

 grip (assuming some sort of grip with switches)

 Trim on the ebus, I would assume that is pitch trim.  How about roll 

 trim?  Rudder trim?

 Larry Rosen

 #356

 John Testement wrote:

> I am pretty close to finalizing my electrical system and would really 

> like to have some knowledgeable folks give it a rigorous critique. I 

> have attached a Word document with my objectives, panel layout and 

> schematic. If any of you are willing, I would really appreciate your 

> taking the time to study the design and give me your recommendations.

>  

> Feel free to contact me offline or call me at 804-303-1927

>  

> Thanks in advance to those who give me some input.

>  

> John Testement

> jwt(at)roadmapscoaching.com <mailto:jwt(at)roadmapscoaching.com>

> 40321

> Richmond, VA

> FWF, engine, wiring

> do not archive

>

> -- 

>

jwt(at)roadmapscoaching.c
Guest

Posted: Sun Feb 11, 2007 6:36 pm Post subject: Electrical System Critique

Thank you Tim, Larry, Jesse, and Carl for you inputs. 



My guess is that there are a lot of us deliberating the numerous options and

trade offs on the electrical system. I would like to encourage us to get a

useful dialog going to sort through the pros and cons of the various

approaches.



Based on what I have learned, I have changed my approach considerably.  I

have attached my new design as well as the old design (as a PDF for those

who could not open it before).  Let's continue to critique the approach for

everyone's benefit.



Tim made some really good points about having independent power (not on the

cranking battery) to the Cheltons, Eng. Monitor and Elect. Ignition for

engine start. This caused me to drop the idea of having a 2nd battery

available for cranking and use the second battery for start-up avionics and

Ebus backup. The main changes I have made are:



I am going with one large main battery - Odyssey 925, 25AH; and a smaller

12AH auxiliary battery (much like Tim's).



During engine start I will run the Ebus (PFD, Eng Mon and E Ign) off of the

Aux battery while cranking from the main battery. After start, I will turn

off the Ebus alternate feed, turn on the Avionics switch, and run everything

off the main battery. I will run the E Ign. off the aux battery (everything

is really running off the alternator during flight anyway). 



I have moved the pitot heat and the fuel boost pump to the main bus.



If the alternator fails I will switch to the Ebus alt feed, manually load

shed the main bus (most loads are on switches anyway). And if I need fuel

boost or pitot, I can turn the main bus back on. The only downside is if the

main battery fails I can only power the Ebus from the aux battery.



I took the contactor off the aux battery since the load is under 15A and a

contactor would draw 1A during an emergency. I don't have an Aux battery

switch (other than the Ebus alt feed switch) since I can't think of a need

for one. The Aux battery will be charged through a diode to the main bus and

the E. Ign is tied through a breaker.



I put the Eng. Monitor on the Ebus since it will be on during start up. I

will be using the AFS3400 which gives me full EFIS back up with its own

internal battery. 



Some concerns and questions: I am running #8 from the alternator to the main

bus. The wire size chart (AC43.13) says a #8 wire is good for 70A at 10ft.

Others are using #6 to go from alternator to the main bus. Do I have a

problem? 

Should I put the smaller aux battery under the flap tunnel or next to the

main battery for W&B? What is a good/light 12AH battery? 

Is the Ebus diode really needed in this design? 

Should the main battery be grounded locally as well as running to the

firewall?



Let me know what you think and contribute any ideas for the benefit of all

the others who are working through their designs.



John Testement

jwt(at)roadmapscoaching.com

40321

Richmond, VA

FWF, engine, wiring





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LarryRosen

Joined: 16 Jan 2006
Posts: 415
Location: Medford, NJ

Posted: Sun Feb 11, 2007 8:29 pm Post subject: Electrical System Critique

Reply below



John Testement wrote:

 	  Quote: 	
		   Thank you Tim, Larry, Jesse, and Carl for you inputs. 



 My guess is that there are a lot of us deliberating the numerous options and

 trade offs on the electrical system. I would like to encourage us to get a

 useful dialog going to sort through the pros and cons of the various

 approaches.

   

I think I have considered every different type electrical design.  It 
	


went something like this: Dual alternator single battery, single 

alternator dual battery, duel alternator duel battery, then back to a 

dual alternator single battery design, which is where I am now.  An now 

with your comments I am considering a small battery just for start up.  

My plan was to use the internal battery in the AFS-3400 to run the 

engine monitor during start.  All other avionics off.

 	  Quote: 	
		   Based on what I have learned, I have changed my approach considerably.  I

 have attached my new design as well as the old design (as a PDF for those

 who could not open it before).  Let's continue to critique the approach for

 everyone's benefit.



 .....



 If the alternator fails I will switch to the Ebus alt feed, 

Shut off the master battery contactor?
	


 	  Quote: 	
		   manually load shed the main bus (most loads are on switches anyway). 

And then turn on the master battery contactor to use the main battery 
	


and the standby battery?

 	  Quote: 	
		   And if I need fuel

 boost or pitot, I can turn the main bus back on. The only downside is if the

 main battery fails I can only power the Ebus from the aux battery.

   

If you do lose the main battery, won't the alternator still supply 
	


power, although in may not be a stable?

 	  Quote: 	
		   ...



 Some concerns and questions: I am running #8 from the alternator to the main

 bus. The wire size chart (AC43.13) says a #8 wire is good for 70A at 10ft.

 Others are using #6 to go from alternator to the main bus. Do I have a

 problem? 

   

I am using AC 43.13-1B Acceptable Methods, Techniques, and Practices - 
	


Aircraft Inspection and Repair table 11-3 DC wire and circuit protector 

chart.  It recommends 8AWG up to 50 amp fuse or breaker and 6AWG for an 

80amp breaker and 70amp fuse.  But, I am sure the devil is in the 

details. 11-49 says, "... This chart was prepared for the conditions 

specified....  In general, the chart is conservative for all ordinary 

aircraft electrical installations"  However Table 11-9 Current carrying 

capacity and resistance of copper wire.  Figure 11-2 does say 8AWG wire 

and 70 amps.    Since the continuous load is not 60 amps I would think 

8AWG is  not a problem.  That being said I am using 6AWG.  I would like 

to know more about the details.

 	  Quote: 	
		   Should I put the smaller aux battery under the flap tunnel or next to the

 main battery for W&B? What is a good/light 12AH battery? 

 Is the Ebus diode really needed in this design?

If you find one let me know
	


 	  Quote: 	
		    

 Should the main battery be grounded locally as well as running to the

 firewall?



   

I think this would give more problems with ground loops.
	


 	  Quote: 	
		   Let me know what you think and contribute any ideas for the benefit of all

 the others who are working through their designs.



 John Testement

 jwt(at)roadmapscoaching.com

 40321

 Richmond, VA

 FWF, engine, wiring

_________________
Larry Rosen
#40356
N205EN (reserved)
<http>

jesse(at)saintaviation.co
Guest

Posted: Mon Feb 12, 2007 4:42 am Post subject: Electrical System Critique

Responses below.



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694



--

john_rv10(at)yahoo.com
Guest

Posted: Mon Feb 12, 2007 9:39 am Post subject: Electrical System Critique

Hi John,  

   

I am also struggling with this design and am probably two steps behind you.  

   

I like the way you have laid yours out, combining physical location with the electrical diagram. This helps me conceptualise.  

   

My own thoughts are not dissimilar to yours with a couple of variations. I am keen to bullet proof my electrical system so at a conceptual level what I am thinking is as follows:-  

   

<![if !supportLists]>·         <![endif]>Two batteries of equal size so you can change them out alternately and always have a relatively new battery for the avionics/endurance buss. Two 17AH batteries should suffice  

<![if !supportLists]>·         <![endif]>Run two fairly equal size busses, one with the main airframe electrics as you have done, the second with the critical to flight safety avionics etc. The critical to flight safety buss might be on two busses, an avionics buss and an endurance buss. To balance out the busses I am considering putting the engine monitor system on the main power buss because I want it for engine start and if I lose a circuit I figure I can live without this for the time it takes to sort out what has happened and what I need to do. If necessary, completing the rest of the flight without it is probably OK if not desirable. As pointed out, most items on the main buss are separately switched, so after things settle you can switch as desired to get back what you can afford to carry.  

<![if !supportLists]>·         <![endif]>Set the batteries up so you can choose to run either battery with either circuit. If both batteries are down the back, this creates a problem with added wire weight to my mind, because you need to run three 4AWG wires from the back if you plan to use both batteries to crank, and two 4AWG plus 1 2AWG if you plan to use one battery to crank. We live in Australia so we don’t get the freezing conditions where I plan to do most my flying, so I like the idea of using the older battery on the power circuit, using it to crank the engine on its own, and at the first sign of not doing that task well, change that battery out for a new one and rotate batteries. I recognize that this approach won’t suit all situations. I would like to put the main battery up the front so I can run very short wires from it to crank the engine, but I am not sure yet whether this is appropriate from a weight and balance perspective. I do like Jesse Saint’s logic from a weight and balance perspective with doing this.  

<![if !supportLists]>·         <![endif]>Install two alternators which are switched to run either/or, not both because of the complexity associated with trying to get both alternators working at the same time, plus I think it is better redundancy planning this way.  

<![if !supportLists]>·         <![endif]>Run one electronic and one mag ignition as you have done, so that in the absolute worse case scenario the engine keeps running on the mag.  

<![if !supportLists]>·         <![endif]>No vacuum system because of their weight and inherent unreliability.  

<![if !supportLists]>·         <![endif]>Run over voltage protection on both alternators because of the damage that can be done to everything without it.  

   

That’s about where I am with my thinking at this stage and I am now ready to move to the more detailed planning phase.  

   

Would you please post an ACAD version of your layout if you have one?  

   

Thanks very much for kicking this thread off, it is very helpful.  

   

John Cleary  

(finishing wings, started fuse)  

   

   

--

jwt(at)roadmapscoaching.c
Guest

Posted: Sat Feb 17, 2007 7:40 am Post subject: Electrical System Critique

John, Larry

  

 I also liked the idea of  2 same size batteries (17ah) and an annual swap. The concern I ran into was  if you use one for cranking and the other for the start-up avionics, I  would have only half the cranking power that I would have had with the one 25ah  battery. According to Tim, you want to start up your Cheltons as well as your  engine monitor before cranking and you do not want to have these or the e.  ignition on the cranking battery (will re-boot the Cheltons and this takes some  time). If I tie the two 17ah batteries together for cranking then I have  tied the avionics to the cranking batteries.  This led me to having one  larger cranking battery and one smaller battery for start-up avionics, e.  ign., and essential bus backup. Is there an option I am missing  here?

  

 I dropped the idea of a  second alternator after discussions with several people. The main reason is that  if I have any electrical failure, I am going to land as soon as possible. I do  not need a second alternator to take me  to the end of my fuel endurance  (might be a dangerous temptation to keep going). With 2 quality RG batteries I  should get about 1 1/2 hours of backup (plus my AFS3400 internal battery - 1  hr.). This should easily get me to an airport or instrument approach if IFR. The  other reason was the cost of the accessory pad back up alternator - about  $1,000.

  

 I don't want to sound  like I am any kind of expert or know the right answer. So please challenge my  thinking. 

  

 Couple of issues I am  struggling over now:

 1) Lightspeed suggest  that you run a 18awg shielded power wire to a breaker and then all the way back  to the battery. I am resisting this, thinking of running the shielded wire to  the breaker, then the 2nd battery bus at the panel, I am not sure that I will  not get ignition noise if I do this. What have others done and what has been  your experience with ignition noise?

 2) I can't decide if I  should put a switch between the 2nd battery and the ebus alternate feed (see  attached schematic). 

 3) Still looking for a  good 12-17ah small/light 2nd battery.

  

 Thanks for all the  inputs

  

  John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

 Richmond, VA

FWF, engine,  wiring

   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] 



 

  

Hi John, 

  

I am also struggling with this design and am probably  two steps behind you. 

  

I like the way you have laid yours out, combining  physical location with the electrical diagram. This helps me  conceptualise. 

  

My own thoughts are not dissimilar to yours with a  couple of variations. I am keen to bullet proof my electrical system so at a  conceptual level what I am thinking is as follows:- 

  

<![if !supportLists]>·          <![endif]>Two batteries of equal size so you  can change them out alternately and always have a relatively new battery for the  avionics/endurance buss. Two 17AH batteries should suffice 

<![if !supportLists]>·          <![endif]>Run two fairly equal size busses,  one with the main airframe electrics as you have done, the second with the  critical to flight safety avionics etc. The critical to flight safety buss might  be on two busses, an avionics buss and an endurance buss. To balance out the  busses I am considering putting the engine monitor system on the main power buss  because I want it for engine start and if I lose a circuit I figure I can live  without this for the time it takes to sort out what has happened and what I need  to do. If necessary, completing the rest of the flight without it is probably OK  if not desirable. As pointed out, most items on the main buss are separately  switched, so after things settle you can switch as desired to get back what you  can afford to carry. 

<![if !supportLists]>·          <![endif]>Set the batteries up so you can  choose to run either battery with either circuit. If both batteries are down the  back, this creates a problem with added wire weight to my mind, because you need  to run three 4AWG wires from the back if you plan to use both batteries to  crank, and two 4AWG plus 1 2AWG if you plan to use one battery to crank. We live  in Australia so we don’t get the freezing conditions where I plan to do most my  flying, so I like the idea of using the older battery on the power circuit,  using it to crank the engine on its own, and at the first sign of not doing that  task well, change that battery out for a new one and rotate batteries. I  recognize that this approach won’t suit all situations. I would like to put the  main battery up the front so I can run very short wires from it to crank the  engine, but I am not sure yet whether this is appropriate from a weight and  balance perspective. I do like Jesse Saint’s logic from a weight and balance  perspective with doing this. 

<![if !supportLists]>·          <![endif]>Install two alternators which are  switched to run either/or, not both because of the complexity associated with  trying to get both alternators working at the same time, plus I think it is  better redundancy planning this way. 

<![if !supportLists]>·          <![endif]>Run one electronic and one mag  ignition as you have done, so that in the absolute worse case scenario the  engine keeps running on the mag. 

<![if !supportLists]>·          <![endif]>No vacuum system because of their  weight and inherent unreliability. 

<![if !supportLists]>·          <![endif]>Run over voltage protection on both  alternators because of the damage that can be done to everything without  it. 

  

That’s about where I am with my thinking at this stage  and I am now ready to move to the more detailed planning  phase. 

  

Would you please post an ACAD version of your layout if  you have one? 

  

Thanks very much for kicking this thread off, it is very  helpful. 

  

John  Cleary 

(finishing wings, started  fuse)

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GenGrumpy(at)aol.com
Guest

Posted: Sat Feb 17, 2007 7:49 pm Post subject: Electrical System Critique

For what it's worth.

  

 My 2 batteries automatically come together when cranking, wired it that way so that the start position of the ignition uses both (Avionics systems did this in the panel).

  

 Lightspeed?  You need to run the hot wire through either a fuse or breaker and tie it directly to the battery.  Don't tie it to a bus relay that can fail on you.

  

 As an example, during flight test I lost an entire bus unexpectedly.

  

 Troubleshooting found that the battery switch wire to the solenoid pulled out of the terminal, so the solenoid lost its ground, and the bus went dead.

  

 I wouldn't want my Lightspeed to go dead because of that.

  

 And Klaus says that if you shut the battery solenoid off, and the battery goes down to 4-5 volts, the light speed will still work!!

  

 So........don't wire your lightspeed into a battery bus controlled by a battery solenoid!!

  

 Grumpy

  

 do not archive

  

 In a message dated 2/17/2007 9:42:33 AM Central Standard Time, jwt(at)roadmapscoaching.com writes:

  	  Quote: 	
		   John, Larry

  

 I also liked the idea of 2 same size batteries (17ah) and an annual swap. The concern I ran into was if you use one for cranking and the other for the start-up avionics, I would have only half the cranking power that I would have had with the one 25ah battery. According to Tim, you want to start up your Cheltons as well as your engine monitor before cranking and you do not want to have these or the e. ignition on the cranking battery (will re-boot the Cheltons and this takes some time). If I tie the two 17ah batteries together for cranking then I have tied the avionics to the cranking batteries.  This led me to having one larger cranking battery and one smaller battery for start-up avionics, e. ign., and essential bus backup. Is there an option I am missing here?

  

 I dropped the idea of a second alternator after discussions with several people. The main reason is that if I have any electrical failure, I am going to land as soon as possible. I do not need a second alternator to take me  to the end of my fuel endurance (might be a dangerous temptation to keep going). With 2 quality RG batteries I should get about 1 1/2 hours of backup (plus my AFS3400 internal battery - 1 hr.). This should easily get me to an airport or instrument approach if IFR. The other reason was the cost of the accessory pad back up alternator - about $1,000.

  

 I don't want to sound like I am any kind of expert or know the right answer. So please challenge my thinking. 

  

 Couple of issues I am struggling over now:

 1) Lightspeed suggest that you run a 18awg shielded power wire to a breaker and then all the way back to the battery. I am resisting this, thinking of running the shielded wire to the breaker, then the 2nd battery bus at the panel, I am not sure that I will not get ignition noise if I do this. What have others done and what has been your experience with ignition noise?

 2) I can't decide if I should put a switch between the 2nd battery and the ebus alternate feed (see attached schematic). 

 3) Still looking for a good 12-17ah small/light 2nd battery.

  

 Thanks for all the inputs

  

  John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

 Richmond, VA

FWF, engine, wiring



	


 

  [quote][b]

Scott Keadle

Joined: 10 Jan 2006
Posts: 31
Location: Lake Norman, North Carolina

Posted: Sun Feb 18, 2007 6:01 am Post subject: Re: Electrical System Critique

All,



I have my panel completed from SteinAir, and was planning on running two alternators, because I didn't think that it was possible to charge two batteries simultaneously with one alternator. Is this correct? If not, then I think I could just charge both with one 60amp alternator. Honestly, I could ask Stein, but I'm too embarrassed to aggravate him any further with a question that I probably already asked him several months ago!



I am running two seperate busses, each of which is capable of operating the airplane in IFR conditions indefinitely. My thought was that if I were going to count on a "backup" system, then I should be constantly monitoring that system for operational readiness, lest I turn to the "backup" and find that it doesn't work when I really need it (this seems common in the typical small business computer backup, for instance).



I am also running dual Lightspeed ignitions, and will run separate physical routing of each wire directly to the battery, in case of a master-solenoid failure, which is actually not that uncommon and pretty much unpreventable. The seperate physical routing is in case of something weird happening to the wire bundle (fire, big toe, AAA from spamcan ground defenses, etc.).



I too, am just now realizing the starter/avionics clash for battery power, and trying to decide how to handle the situation. It may be as simple as starting on the "backup" bus, which doesn't have the Chelton's on it, and using a "cranking" style battery  on that bus. I would appreciate any suggestions.



I have a wiring diagram that I would be happy to share if anyone cared to see it, but it is a hard copy produced by SteinAir, and I'm not quite sure I know how to get it onto the computer. I am copying this message to Stein, so maybe he has a digital copy that he can send to the list.



Scott



[quote="GenGrumpy(at)aol.com"]For what it's worth.

  

 My 2 batteries automatically come together when cranking, wired it that way so that the start position of the ignition uses both (Avionics systems did this in the panel).

  

 Lightspeed?  You need to run the hot wire through either a fuse or breaker and tie it directly to the battery.  Don't tie it to a bus relay that can fail on you.

  

 As an example, during flight test I lost an entire bus unexpectedly.

  

 Troubleshooting found that the battery switch wire to the solenoid pulled out of the terminal, so the solenoid lost its ground, and the bus went dead.

  

 I wouldn't want my Lightspeed to go dead because of that.

  

 And Klaus says that if you shut the battery solenoid off, and the battery goes down to 4-5 volts, the light speed will still work!!

  

 So........don't wire your lightspeed into a battery bus controlled by a battery solenoid!!

  

 Grumpy

  

 do not archive

  

 In a message dated 2/17/2007 9:42:33 AM Central Standard Time, jwt(at)roadmapscoaching.com writes:

  	  Quote: 	
		   John, Larry

  

 I also liked the idea of 2 same size batteries (17ah) and an annual swap. The concern I ran into was if you use one for cranking and the other for the start-up avionics, I would have only half the cranking power that I would have had with the one 25ah battery. According to Tim, you want to start up your Cheltons as well as your engine monitor before cranking and you do not want to have these or the e. ignition on the cranking battery (will re-boot the Cheltons and this takes some time). If I tie the two 17ah batteries together for cranking then I have tied the avionics to the cranking batteries.  This led me to having one larger cranking battery and one smaller battery for start-up avionics, e. ign., and essential bus backup. Is there an option I am missing here?

  

 I dropped the idea of a second alternator after discussions with several people. The main reason is that if I have any electrical failure, I am going to land as soon as possible. I do not need a second alternator to take me? to the end of my fuel endurance (might be a dangerous temptation to keep going). With 2 quality RG batteries I should get about 1 1/2 hours of backup (plus my AFS3400 internal battery - 1 hr.). This should easily get me to an airport or instrument approach if IFR. The other reason was the cost of the accessory pad back up alternator - about $1,000.

  

 I don't want to sound like I am any kind of expert or know the right answer. So please challenge my thinking. 

  

 Couple of issues I am struggling over now:

 1) Lightspeed suggest that you run a 18awg shielded power wire to a breaker and then all the way back to the battery. I am resisting this, thinking of running the shielded wire to the breaker, then the 2nd battery bus at the panel, I am not sure that I will not get ignition noise if I do this. What have others done and what has been your experience with ignition noise?

 2) I can't decide if I should put a switch between the 2nd battery and the ebus alternate feed (see attached schematic). 

 3) Still looking for a good 12-17ah small/light 2nd battery.

  

 Thanks for all the inputs

  

  John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

 Richmond, VA

FWF, engine, wiring



	


 

   	  Quote: 	
		  [b]

_________________
Scott Keadle
14A, Lake Norman Airpark
N426AK RV-10, final assembly
N246SK, Giles 202, flying

jwt(at)roadmapscoaching.c
Guest

Posted: Sun Feb 18, 2007 7:49 am Post subject: Electrical System Critique

Grumpy,

  

 Would you run the  shielded wire all the way to the back of the plane to the battery or just to a  battery buss (non-contactor) at the panel?

  

  John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

 Richmond, VA

FWF, engine, wiring

 do not archive

   From: owner-rv10-list-server(at)matronics.com  [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of  GenGrumpy(at)aol.com

Sent: Saturday, February 17, 2007 10:48  PM

To: rv10-list(at)matronics.com

Subject: Re: RV10-List:  Electrical System Critique

 

  For what it's worth.

  

 My 2 batteries automatically come together when cranking, wired it that way  so that the start position of the ignition uses both (Avionics systems did this  in the panel).

  

 Lightspeed?  You need to run the hot wire through either a fuse or  breaker and tie it directly to the battery.  Don't tie it to a bus  relay that can fail on you.

  

 As an example, during flight test I lost an entire bus unexpectedly.

  

 Troubleshooting found that the battery switch wire to the solenoid pulled  out of the terminal, so the solenoid lost its ground, and the bus went  dead.

  

 I wouldn't want my Lightspeed to go dead because of that.

  

 And Klaus says that if you shut the battery solenoid off, and the battery  goes down to 4-5 volts, the light speed will still work!!

  

 So........don't wire your lightspeed into a battery bus controlled by a  battery solenoid!!

  

 Grumpy

  

 do not archive

  

 In a message dated 2/17/2007 9:42:33 AM Central Standard Time,  jwt(at)roadmapscoaching.com writes:

  	  Quote: 	
		     John,    Larry

    

   I also    liked the idea of 2 same size batteries (17ah) and an annual swap. The    concern I ran into was if you use one for cranking and the other for the    start-up avionics, I would have only half the cranking power that I would have    had with the one 25ah battery. According to Tim, you want to start up your    Cheltons as well as your engine monitor before cranking and you do not want to    have these or the e. ignition on the cranking battery (will re-boot the    Cheltons and this takes some time). If I tie the two 17ah batteries    together for cranking then I have tied the avionics to the cranking    batteries.  This led me to having one larger cranking battery and one    smaller battery for start-up avionics, e. ign., and essential bus    backup. Is there an option I am missing here?

    

   I    dropped the idea of a second alternator after discussions with several people.    The main reason is that if I have any electrical failure, I am going to land    as soon as possible. I do not need a second alternator to take me  to the    end of my fuel endurance (might be a dangerous temptation to keep going). With    2 quality RG batteries I should get about 1 1/2 hours of backup (plus my    AFS3400 internal battery - 1 hr.). This should easily get me to an airport or    instrument approach if IFR. The other reason was the cost of the accessory pad    back up alternator - about $1,000.

    

   I    don't want to sound like I am any kind of expert or know the right answer. So    please challenge my thinking. 

    

   Couple    of issues I am struggling over now:

   1)    Lightspeed suggest that you run a 18awg shielded power wire to a breaker and    then all the way back to the battery. I am resisting this, thinking of running    the shielded wire to the breaker, then the 2nd battery bus at the panel, I am    not sure that I will not get ignition noise if I do this. What have others    done and what has been your experience with ignition  noise?

   2) I    can't decide if I should put a switch between the 2nd battery and the ebus    alternate feed (see attached schematic). 

   3)    Still looking for a good 12-17ah small/light 2nd battery.

    

   Thanks    for all the inputs

    

      John Testement

jwt(at)roadmapscoaching.com (jwt(at)roadmapscoaching.com)

40321

   Richmond, VA

FWF, engine,    wiring



	


 

 	  Quote: 	
		  



href="http://www.matronics.com/Navigator?RV10-List">http://www.matronics.com/Navigator?RV10-List

href="http://forums.matronics.com">http://forums.matronics.com



	
-- No virus found in this  Edition.   

  

--

 2/17/2007

     [quote][b]

jwt(at)roadmapscoaching.c
Guest

Posted: Sun Feb 18, 2007 8:05 am Post subject: Electrical System Critique

Scott - and others,



Based on all of great inputs on and off line I am now leaning back towards

the 2 PC680 17ah battery scheme. I will allow the 2nd battery to

independently run avionics during start up. I would provide the option to

tie the 2nd battery to the main battery through a contactor if in a cold

situation the main battery cannot start the engine. 



Once started I can also tie the 2nd battery to the main bus to let it

charge. If the 1st battery fails and I need main bus items I can power the

main bus from the second battery. 



Unless I am overlooking something (which I usually do), this seems like the

best of all worlds - independent avionics on start, annual rotation of

batteries, minimal weight impact, longer ebus backup time.



Please give me your reactions - diagram attached.



John Testement

jwt(at)roadmapscoaching.com

40321

Richmond, VA

FWF, engine, wiring



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